An apparatus of this type has been disclosed in German Pat. No. 11 89 513, in which the winding spindle is driven by an intermittent drive means, for example a braking motor (see also German Pat. No. 19 44 223), when a spiral of binding coils is rotated to introduce it into the above mentioned row of holes. The braking motor was stopped again at the end of the spiralling operation, the coil cut to length and the winding spindle started up again once a new pack of sheets had been inserted in to the spiralling unit. According to German Pat. No. 11 89 513, the winding spindle is designed in such a way that if the coil is wound in defectively, for example owing to a blocked hole in the row of holes, the coil is stopped automatically as the wire can rise from the winding spindle.
The known apparatus suffered from the problem that driving the winding spindle by means of a braking motor, i.e. a motor which could be switched on and off with high frequency, meant that the motor had to be accelerated from standstill to its nominal speed during each winding process and then braked to a standstill again. The spiral was then cut to length.
The performance i.e. the number of operations per unit time (the number of spirals introduced per unit time), of the known apparatuses cannot be varied at will. As the winding tool can only operate while the pack of sheets is ready for winding in the spiralling unit and, moreover, time has to be allowed for cutting the ends of the spiral, it is necessary to carry out the actual spiralling operation in a very short time. A little more than a second remains for the spiralling operation if the apparatus carries out 30 operations per minute. Attempts have been made to operate with braking motors having higher performances, but they did not lead to any improvement in the rate of operation. Attempts have also been made to operate with a continuous drive and to switch on the winding spindle by means of mechanical or electromechanical couplings. These attempts did not produce a practically serviceable apparatus with a higher performance either.
German Pat. No. 19 44 223 describes an apparatus designed to have a higher performance, in which the spirals are continuously produced and cut to length, but not rotated directly into a pack of sheets. Instead the spirals are stored for an intermediate period and then rotated into the pack using a special winding device. Although the performance could be increased using this apparatus, it was very complicated and expensive to produce.